You just used it. Love Potions are for mating your tamagotchi friends if they are both adults and have hearts for the friendship. After the hearts dissapear, you can get a baby. Your parent will babysit the baby untill the baby goes to sleep. If you want the parent to stay, pause it all night. The parent leaves and then you can have the baby as your pet, and the generation goes on and on untill one of your tamagotchis dies. I hope I helped.
TP